I honestly don't remember typing that one up - lol
I know when I was building free sites, I had 25 warning pages, 20 main pages & 30 gallery pages. I numbered each 01warn, 02warn...25warn; 01main, 02main...20main; 01gallery, 02gallery...30gallery
So on the 1st day, I'd build with 01warn, 01main & 01gallery.
4th day it'd be 04warn, 04main, 04gallery.
21st day, it'd be 21warn, 01main, 21gallery (because I used 20main the day before)
31st day, it'd be 01warn, 11main, 31gallery
I'm not sure how many different combinations that gives you, but it's a shitload
So just go in order - once you get to the end of one, start back over with it while you keep going with the others.